The invention relates to voltage regulators and specifically relates to an improved voltage reference circuit used in a voltage regulator. A basic stacked bandgap reference is found in the Brokaw U.S. Pat. No. Re. 30,586 patent reissued from U.S. Pat. No. 3,887,863 which originally issued June 3, 1975. Here a pair of ratioed current density transistors have their bases coupled together and are biased so that the transistor collectors are at the same potential. The differential base to emitter voltage (.DELTA.V.sub.BE) appears across a resistor in series with the emitter of the low current density transistor. The combined emitter currents of the two transistors are returned to ground through a common stacking resistor. The voltage across the stacking resistor therefore is proportional to absolute temperature (PTAT). When this voltage is combined with the V.sub.BE of the high current density transistor, and the combination made close to the bandgap of silicon extrapolated to absolute zero (about 1.25 volts), a temperature compensated reference voltage V.sub.REF is achieved.
When this reference voltage is used to establish the regulation level in a regulated power supply, the output voltage of the regulator will be substantially independent of temperature. Typically the regulator will include a voltage divider connected across the output terminals and it has a tap operating at V.sub.REF. The regulator also includes a current pass device connected between the power input terminal and the output terminal. The pass device has its conductivity controlled so that the divider tap is at V.sub.REF. Such a divider is desirably stiff so that considerable quiescent current is required. Quiescent current is defined as that current flowing to ground in the regulator circuit and which does not contribute to current flow in the load. Thus, quiescent current is wasted and it is desirable to reduce or eliminate it, particularly in battery operated equipment.